In the processing of grease trap waste, the waste is typically loaded into a containment vessel configured to provide even heating of the waste so as to promote stratification of the waste into different layers. Heating of the waste is typically accomplished through the combustion of a petroleum based fuel, such as natural gas or light heating oil. The proper time and temperature relationship promotes stratification to form a bottom layer of mostly water. Directly above the layer of water will be a region containing food scrap residue. The top layer will consist of rich brown grease with viscosity, combustion, and heating value characteristics similar to the petroleum based product commonly known as Bunker 5, Bunker 6 or Heavy Fuel Oil. Typically, the brown grease layer is extracted to a separate storage vessel for transport to the end user.